The invention discloses an exposure sensor based on memristors connected in reverse series. The exposure sensor comprises a first power supply V1, a second power supply V2, a switch K, a photoelectric module, a current-limiting module, an memristor module, a difference-acquiring module, an amplifying module, and an increasing module. The first power supply V1 or the second power supply V2 forms a circuit successively with the switch K, the photoelectric module, the current-limiting module and the memristor module. The memristor module includes memristors Mz1, Mz2, Mj1 and Mj2. The Mj1 and the Mj2 are completely the same. The Mz1 and the Mj1 are connected in series. The Mz2 and the Mj2 are connected in series. A series branch formed by the Mz1 and the Mj1 is connected in parallel with a series branch formed by the Mz2 and the Mj2. The difference-acquiring module is connected with the memristor module. The amplifying module is connected to the difference-acquiring module. The increasing module is connected with the amplifying module. The exposure sensor is large in exposure measurement range, high in sensitivity, suitable for the measurement of large exposure and long exposure, and is simple in circuit, avoids an influence of a memristor resistance value change on the loop current and the exposure measurement of the sensor, and is low in measurement error and easy to use.